1.5(a+b)^n-2/3(a-b)^n-3/5(a+b0^n+0.4(a-b）^n11.5(a+b)^n-2/3(a-b)^n-3/5(a+b0^n+0.4(a-b）^n2已知x-y=2(1)求代数式3-x+y的值（2）求代数式（x-y)^2-2x+2y的值3-9x^k+1-4x^k+12x^k+1+5x^k+x^k+1

Question

1.5(a+b)^n-2/3(a-b)^n-3/5(a+b0^n+0.4(a-b）^n
【1】1.5(a+b)^n-2/3(a-b)^n-3/5(a+b0^n+0.4(a-b）^n
【2】已知x-y=2
(1)求代数式3-x+y的值
（2）求代数式（x-y)^2-2x+2y的值
【3】-9x^k+1-4x^k+12x^k+1+5x^k+x^k+1

Answer 1

【1】1.5(a+b)^n-2/3(a-b)^n-3/5(a+b0^n+0.4(a-b）^n
=(1.5-3/5)(a+b)^n+(0.4-2/3)(a-b)^n
=0.9(a+b)^n-4/15(a-b)^n
【2】已知x-y=2
(1)3-x+y
=3-(x-y)
=3-2
=1
(2）（x-y)^2-2x+2y
=（x-y)^2-2(x-y)
=2^2-2×2
=4-4
=0
【3】
-9x^k+1-4x^k+12x^k+1+5x^k+x^k+1
=(-9-4+12+5+1)x^k+1+1+1
=5x^k+3